The Vatican announced that the Pope's health had worsened on Thursday when he developed a urinary tract infection that later brought on "septic shock and a cardio-circulatory collapse".

He was "immediately informed about the gravity of his condition", papal spokesman Joaquin Navarro-Valls told reporters at the Vatican on Friday.

But the Pope decided not to return to Rome's Gemelli hospital - and is being treated in his apartment by a team of four top consultants and his private doctor Renato Buzzonetti.

Church appointments

On Friday morning, he was "still lucid, fully conscious and extraordinarily serene", the spokesman said.

The Pope was able to make a sign of the Cross on Friday morning as aides read the scriptures to him, he added.

Pilgrims gather in St Peter's Square to pray for the Pope

Later on Friday, the Vatican announced that the Pope had approved the appointment of 17 new bishops and archbishops and accepted the resignation of six others.

Millions of Catholics across the world have been gathering in churches and in the open air to pray for the Pope.

In Rome, the Pope's vicar Cardinal Camillo Ruini is due to preside over a mass at St John Lateran Basilica, starting at 1900 local time (1700 GMT).

Police have imposed traffic restrictions around the Vatican and authorities are making plans to deal with a huge influx of pilgrims anxious to be present in the event of an announcement of the Pope's death.

Cardinals - who will have the duty of electing a new pope - are beginning to arrive in Rome from all over the world, Italian media have reported.

'Expression of love'

In the Pope's homeland, Poland, churches have been packed with worshippers.

The Archbishop of Krakow, Franciszek Macharski - a long-time friend of the Pope - told his audience: "Do not feel shame at showing your emotion and at shedding tears."

Soon he will carry his cross into eternity and we will have to study hard the footprints he has left